1. Field of the Invention
The present invention relates to a process for producing oxazolone derivatives.
The oxazolone derivatives are used as intermediates for medicines and pesticides.
For example, compounds of the formula ##STR2## can be hydrolyzed under an acidic condition into .delta.-aminolevulinic acid (ALA) of the formula: ##STR3## usable as intermediates for the biosynthesis of chlorophyll or heme or as herbicides.
2. Description of the Prior Art
It is known that the oxazolone derivatives of the general formula (III) are obtained by reacting a compound of the general formula (I) with a compound of the general formula (II) in the presence of .gamma.-picoline (Izv. Akad. Nauk SSSR, Ser. Khim., 1970, 724). ##STR4## wherein Ar represents an aromatic hydrocarbon residue, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each represent a hydrogen atom, a halogen atom or an organic residue, R.sup.5 represents a hydrogen residue and X represents a halogen atom.
Since .gamma.-picoline is used in an amount sufficient for serving as the solvent in the above-described process, it must be recovered and reused to conduct this process on an industrial scale. Since however .gamma.-picoline has a high boiling point and is soluble in water, a high recovering cost is required and the yield is unsatisfactory.